The NTSB preliminary report on a Nov. 15 accident at Waukesha (Wisconsin) County Airport (KUES) cites autopilot anomalies with the Fairchild SA227-AT twin turboprop. The aircraft was substantially damaged, but the single passenger on the Part 135 on-demand cargo flight was uninjured. The two pilots receive minor injuries. Fifty-six dogs on board also survived the crash landing.
According to the NTSB report: “The flight crew reported that the airplane was on an instrument landing system (ILS) approach to Runway 10 at the Waukesha County Airport (UES) when the accident occurred. After air traffic control (ATC) cleared them for the approach and the airplane intercepted the localizer and glideslope for the approach, the flight crew noticed that the command bars on the airplane’s flight director were indicating a climbing right turn.”
The autopilot was in approach mode and tracking the localizer and glideslope. The pilots disconnected the autopilot to continue the approach manually. But upon disconnecting the autopilot, the pilots experienced an immediate roll to the right. They increased power and were able to level the aircraft, but it went through a tree line and hit the ground in a “near wings-level” attitude, ripping the wings from the aircraft.
Icing event?…flight director reflecting onset of sinking/drifting with autopilot masking impending stall/loss of roll control?
What did the altimeter say?